How do you open a disagreement email to a senior colleague?

Open with the decision, not with the disagreement. One sentence that names what you are writing about and what you want — I want to flag one assumption in the migration schedule before we commit — then the acknowledge line. Senior readers scan the first line to decide whether the email needs them now, later or never; if the first line is a preamble, the email is deferred. Do not open with an apology for writing, and do not open with "I hope you don't mind me saying".

Disagreeing by Email in English: Softening Lines That Still Land →